Preparation and application of low rebound liquid alkali-free accelerator for shotcrete

A low rebound alkali-free accelerator (JD accelerator) was developed with aluminum sulfate as the main raw material. The setting time and strength of cement with different dosages of JD accelerator were studied, and the optimal dosage is 8 % of cement quality. The mechanism of acceleration was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), the results showed that JD accelerator accelerated the hydration of C3A and C3S, promoted the formation of AFt, shortened the setting time of cement paste, and improved the early and late strength of cement mortar. Through the field test, the performance of JD accelerator in strength development and rebound of shotcrete under actual working conditions was investigated. Shotcrete with JD accelerator can reach the designed strength in 7 days, and the rebound rate can be controlled at 5.23 %. At the same time, the rebound mechanism of shotcrete was studied.